ON ARACHNIDA. 
411 
position vary according to the manner in which these 
animals hold themselves in a state of repose, and according 
to some peculiar habits. They are very brilliant, and in 
some species offer the appearance of a pupil and an iris. 
The organs of manducation occupy the anterior and lower 
extremity of the trunk. They consist of two mandibles, two 
palpi, a lip, and a kind of epiglottis, or interior tongue. The 
mandibles advance in parallel directions, and are composed of 
two tubular articulations, the first of which is the largest, and 
the terminal one more solid and scaly, in the form of a very 
sharp crook, and having at its extremity a small cleft, destined 
for the passage of a poisonous fluid, which is conducted thither 
by an interior canal, from the base of the first articulation, 
where its reservoir, or the poisonous receptacle exists. The 
palpi, like little feet, especially in my gale , are of the same 
thickness, or filiform, in the females, thicker at their extremity 
in the males, and composed of five, or even six, articulations. 
The jaws are composed of a single piece, in the form of a 
lamina, more or less oval and triangular. The palpi articu- 
late with their summit in the mygale, so that the jaw's in 
reality form the first articulation. However, in the other 
araneides, it is at the base of their internal side, that the 
palpi are inserted. The lip is also of a single piece, the 
figure of which most usually approaches a square, or an oval, 
truncated at its base, and is but an appendage of the anterior 
extremity of the breast. The interior of the mouth, or palate, 
presents a fleshy piece, hairy, in the form of a tongue, which, 
in most of the species, is applied against the internal surface 
of the lip. There is, probably, on each of its sides, an aper- 
ture for the passage of the alimentary fluids. The mandibles, 
no doubt, contribute to manducation ; but though hollow and 
pierced at their extremity, they do not perform the office of a 
sucker. Their use is to retain the insect seized by the 
araneid, and facilitate the compression made upon it by the 
